Protective clothing of many types is now well known for many and varied uses, such as suits for industrial workers, suits for fireman, forest fire fighters, race car drivers and airplane pilots, and suits for use by military personnel, for protection from fire, vapors and harmful substances. Garments include not only complete, hermetic suits, but also individual garments such as trousers, jackets, gloves, boots, hats, head coverings, masks, etc.
Regulations resticting exposure to hazardous environments of various kinds, such as the Occupational Safety and Health Act, make it increasingly necessary to have better and more effective kinds of protective garments. In particular, certain requirements by the U.S. Coast Guard and related requirements by other U.S. government or organizations involve a total protective hermetic suit or envelope around the individual person or fireman. These situations involve cleaning up chemical spills or for fighting chemical fires where the chemical materials are unknown and presumed toxic.
The need for such encapsulating suits for "immediately dangerous to life and health (IDLH)" environments. These sutis must be air tight and worn with a self-contained breathing apparatus. The suit must be nonabsorbent, totally impermeable, and resistant to the widest range of chemicals and reagents. It should also be as fire resistant as possible. Since these suits are being worn by actively working individuals, they should also be flexible, abrasion resistant, light weight, and should maintain their impermeability while being used.
Such garments presently available are almost invariably of thick construction and heavy in weight, and are often fabricated at least in part from materials impermeable to water or water vapor, such as natural and synthetic rubbers and elastomers, chlorinated rubbers, etc.
Protective clothing comprised of laminates of films have the problem of forming "kinks" when bent so as to restrict movement and become cumbersome. Moreover, some of the protective clothing are porous and provide little protection against hazardous chemical vapors.
It is therefore desirable to provide a fabric which, in addition to being flame retardant, also possesses good abrasion resistance, flexibility and heat sealing properties.
U.S. Pat. No. 4,569,088 to Frankburg et al describes a protective garment for protection from high temperatures and occasional splashes of molten metal. The fabric comprises an inner fabric layer of a fibrous polyamide and surface layers of polytetrafluoroethylene fibers. However, the fabric is porous and does not provide any protection against hazardous vapors.
U.S. Pat. No. 2,840,881 describes fibrous structures comprised of a surface layer of nonwoven, intermingled polytetrafluoroethylene fibers and another layer of fibers other than polyetrafluoroethylene fibers. The structures are useful when a lubricating surface is required.
In order to maximize the impermeability of the fabric against all chemical substances and vapors, the plastic films used must be composed of a fusible or meltable polyhalogenated polymer. Additionally, the film itself must be without pin holes, fibers or porosity which lessen the barrier resistance of the actual film. Laminating the continuously formed film to a fabric gains the strength of the woven fabric without interferring with barrier properties of the film. It enhances the flexibility and resistance to failure from flexing of the total laminated fabric. Because of the absolute failsafe requirements of these chemical protective suits and for ease of putting the suit on or taking it off, a second layer of film is also used to form a sandwich. This maximizes the flexibility of a given construction with the total plastic film barrier being split into two layers and being easier to flex than one thick layer.
Note that polytetrafluorethylene (TFE) does not fuse. Sheets of TFE are hot pressed from the powder or fiber to form coalescence into sheets or films which have porosity and poor abrasion resistance.